usb: xhci: add PORTPMSC variable to xhci_hub_control()

usb: xhci: add PORTPMSC variable to xhci_hub_control()

The code handling U1/U2 timeout updates reads and modifies the PORTPMSC
register using the generic 'temp' variable, which is also used for
PORTSC. This makes the code hard to read and increases the risk of mixing
up register contents.

Introduce a dedicated 'portpmsc' variable for PORTPMSC accesses and use
it in both U1 and U2 timeout handlers. This makes the intent clearer and
keeps register operations logically separated.

Signed-off-by: Niklas Neronin <niklas.neronin@linux.intel.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Link: https://patch.msgid.link/20260402131342.2628648-19-mathias.nyman@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>